The present invention relates to demolition equipment and more particularly to heavy duty demolition shears for reducing building and construction materials to scrap for recycling.
Demolition of buildings and steel structures has become important where space is needed to build new structures while the demolishment of such structures must be efficient and be able to reduce all materials to a small enough size for recycling and eventual reuse of metals once melted down and reformed. Burying of scrap materials is simply not even an option anymore. In fact, reprocessing of metal materials from demolition destined for scrape yards for recycling has become a huge business.
Demolition shears have become an important tool for demolition jobs. Bridges and large buildings have significant amounts of metal support, metal reinforced concrete and other metal reinforced structures. Such metal pieces are large and often have multiple connections. Cutting of these metals by saw, grinder or torch has become way too impractical and hazardous. Demotion shears are used to punch through metals and shear the metal structures into small pieces. In fact, metal demolition shears are used to cut metal cables, reinforced concrete, car parts, rods, rebar, rail cars, tanks, pipes, channels and other vehicle frames. Demolition shears can easily shear up to sixteen inch I-beams into small pieces that are only a couple of feet long or less and readily usable for recycling once reduced in size.
Demolition shears are typically mounted on the distal end of a boom structure or dipper stick on a backhoe or excavator. By this arrangement, the shear is actually mobile and capable of moving about a demolition site as well as reaching elevated positions up high in a safe manner. The operation of the shears with one movable and one fixed (or movable) jaw is by hydraulic cylinders.
Prior art FIGS. 1 through 2B generally show the structure of a demolition shear. FIG. 1 shows a prior art heavy duty demolition shear 10 with a frame 12 supporting a lower jaw 14 and pivot 16. The lower jaw 14 has a shear blade side 18, a guide blade side 20 and a cross, tie or chin plate 22 forming a recess 23 therebetween. An upper jaw 24 is connected to the fame 12 and lower jaw 14 at pivot 16. A hydraulic cylinder or actuator 26 also is connected to the frame 12 and a rear portion of the upper jaw 24 The upper jaw 24 has a shear blade side 28, a guide blade side 30 with a distal end shear tip or tang 32. In operation, the upper jaw 24 with replaceable shear blades, passes into the recess 23. In this shear, there is a replaceable shear tip 34 welded onto the end of the upper jaw 24 at its tip or tang 32. The tip 34 needs to be periodically replaced as the shear tip becomes worn as it punches through material to be reduced and further shears along the distal shear blade, distal guide blade and cross cutter blade. Replacement is handled by cutting off the tip 34, suitably with a torch, and welding on a new shear tip 34. Over more time, the upper jaw distal end or tang 32 becomes so worn that it must be cut off and a new tip must be welded on.
In FIGS. 2 through 2B is another prior art heavy duty demolition shear 40 with a lower jaw 42, pivot 44, shear blade side 46, guide blade side 58 and a tie plate 50 forming its recess 52 therebetween. The upper jaw 54 has a shear blade side 56, guide blade side 58 and a tang 60. The tang 60 has a front edge 60a, side faces 60b, top seat 60c, rear seat 60d and bottom seat 60e. In this case, the tang 60 is somewhat more protected from the work piece to be sheared and shear blade edges along the lower shear blade, guide blade and cutter blade with replaceable L-shaped shear tip sections 64. Here the distal end of the upper jaw 54 and front edge of the tang 60 are not protected at all. In time with use, the tang side faces 60b become worn down requiring tightening of the L-shape shear tip sections 64 which detrimentally causes the shorter lower L sections to open up and rotate inward at their top thereby causing the cutting edges to move laterally outward which may cause the shear tip portions to break as they strike the distal lower shear blade 46 or guide blade 48. Total clamping force action between the shear tip or tang 60 and the shear tip sections 64 is absolutely required for the shear tip and tang to work properly together and for the tang 60 to not wear out prematurely. It can be costly to replace these worn parts and such repair efforts require the shear 40 to be taken out of operation.
There is a need for a shear tip that encompasses or encapsulates most, if not all, of the shear tang that is substantially one-piece and is adjustable with shims, to insure complete and total clamping force between the shear tang and the shear tip piece or pieces and to minimize tang side face wear and assure proper alignment of the shear tip on the tang to avoid shear tip breakage.